Coldest weather this season was an EMS base 1 layer, an Arcteryx Delta 1/4 zip, and Arcteryx Atom, and Arcteryx Beta AR for damp and wind protection.On warmer days, just let down the zipper or used the pit zips.
For boots I have heaters (therm-ic) that use AAA's. The rechargeable are fine but run out of gas mid way through the day when it's coldest, but I can change batteries on the fly.
If needed, a thin insulating layer under your helmet will ward off anything required, and a face mask if it's brutally cold.
BTW, EMS is currently running a 1/2 off deal on factory seconds. VERY good deals to be had.